Prevention of foaming in steam generation



, eventual condensate.

' steam is used for the generation of power.

Patented Jan. 1, 1952 UNITED STATES ENT OFFlCE PREVENTION OF FOAMING INSTEAM GENERATION No Drawing. Application September 19, 1942,

Serial No. 459,014

14 Claims. (Cl. 252-321) The present invention relates to antifoamincompositions which are used in steam boilers and similar steamgenerators, evaporators, etc., to overcome the tendency of the watertherein to foam and hence to bring about the priming of the steamgenerator or the like.

One of the objects of the present invention relates to a liquid suitablefor the generation of steam in steam generators and comprising waterretained by the water and neither they nor their decomposition productswill appear in the steam and the resulting condensation thereof. It iswell known in the operation of steam boilers, such as in electric powerplants, railroad locomotives and the like, or in evaporators, that thewater therein, even though initially it shows very little tendency tofoam, will, when the amount of total solids therein approaches arelatively high concentration, develop a very decided tendency to foam.When this occurs, considerable quantities of water are physicallycarried out ofthe boilers or evaporators with the steam,

thus appearing in the steam lines and in the Such priming has manydisadvantages because ittends to contaminate the steam lines, to plug orcorrode'the valves, and under serious conditions may even impair thecylinders and piston rods of the steam engines,

or the impeller blades of turbines in which the Attempts have been madein the past to control this foaming by excessive blowdown of the boilersor by the injection thereinto of such materials as castor oil, tallow,and the like. While these fatty materials have some small degree ofefliciency,

they are, on the other hand, quite deficient in that they introduce newdifliculties which, in some instances, are worse than the conditionsthey are intended to cure. In the first place, these fatty acids orglycerides are unstable under theconditions existing in the boilers,particularly as the pressure and temperatures increase, the hightemperatures leading to rapid decomposition of the glyceridea which, ifany thing, will tend to increase the foaming and priming difficulties.Furthermore, in many instances certainof the decomposition products thusproduced, or sometimes even the materials themselves, have a definitevolatility with steam and will, therefore, steam-distil out of theboilers, thus appearing in the steam and in the condensate. This, ofcourse, is also very undesirable. Furthermore, such types ofantifoamingagents usually have to be employed in relatively largequantities, adding not only to the expense but also to the inconvenienceof operating the steam generators; and those which have a tendency todecompose do so quite rapidly, and hence their effectiveness is of shortduration, which therefore necessitates the continual charging into theboilers or other steam generators of relatively large amounts of theseolder antifoaming agents. Moreover, such antifoaming agents aredifficult to use because the amounts in which they are eflicacious arevery critical, and any overdosage usually aggravates the difiicultyinstead of curing it.

Applicant has now discovered, however, that there is a series ofcompounds, which may be designated as N,N-disubstituted diamides ofcomplex dibasic acids, which are of a high order of efiiciency when usedas an antifoaming and antipriming agent in steam generators.

The materials 'of this invention may be represented by the generalformula wherein Y is an aliphatic radical of relatively large moleculuarsize; Z is the divalent hydrocarbon radical of a halogeno-acid; and X isthe residue from an organic polyamine, whose terminal nitrogen atomsappear'on either side of X in the above formula.

An example of a compound represented by the above formula isN,N-diethylenetriaminobis-N- octadecylacetamide, obtained by thereaction of two mols of N-octadecylchloroacetamide and one ofdiethylenetriamine according to the following equation:

In order to yield an efiicient antifoam material, it appears to benecessary that the alkyl groups, Y, of the formula containing at leastabout 14 carbon atoms each but the radicals Z may be varied within widelimits, such halogeno-acids as .chloroacetic, betachlorobutyric, ando-iodobenzoic being all suitable as starting materials in thepreparation of the N-alkylated amides. Furthermore, the nature of theorganic polyamine, the residue of which is repre- 3 sented by X in theformula, may be varied considerably. Thus, coupling has been effected bymeans of such amines as hydrazine, piperazine, thepolyalgylenepolyamides, alkylenediamines, and the phenylenediamines,yielding efiicient products in every case. Obviously, in the case wherehydrazine is the coupling agent, the (X) of the general formula will beabsent. Also, the alkyl groups on the amido nitrogens may be de-' rivedfrom either primary or secondary amines.

It is to be understood that the formulas recited in the specificationand claims are probable in that the formulas given are believed tozbepossessed by the compounds disclosed, or whose method of preparation isdisclosed, in this specification.

The simplest method of manufacturing the materials of this inventioninvolves the initial formation of the N-alkylated amide of thehalogeno-acid by merely heating the desired amine with the halogeno-acid(or corresponding acid halide) and the subsequent coupling of theproduct by introducing the polyamine and heating until the halogengroups ofthe halogeno-acid have been aminated. This method isillustrated in the following examples of the preparation of materialspossessing value as antifoam agents, but it is to be'understood that Ido not wish to be limited by the examples.

' Example .1.-A mixture of 13.6 grams (0.04

mol) of N-octadecylchloroacetamide and 2.1 grams (0.02 mol) ofdiethylenetriamine was stirred 2 hours at 150-160 C.

Example 2.-A mixture of 12 grams (0.033 mol) ofN-octadecylchloroacetamide and 2 grams (0.016 mol) of 40%. aqueoushydrazine hydrate was'stirred for 3 hours at ISO-160 C., after a briefinitial period at a lower temperature to prevent excessive frothing.

Example 3.-To 0.05 mol of N-octadecylchloro-' acetamide at 150-160 C.,2.2 grams (0.025 mol) of 68% aqueous ethylenediamine was added dropwisewith stirring, and stirring and heating continued 3 hours.

Ema'mple 4.To 0.05 mol of N-octadecylchloroacetamide at 150-160 C., 5grams (0.025 mol) of piperazine hex'ahydrate was added with stirring,and the stirring and heating continued for 2 hours.

Example 5.-To 0.05 mol of N-octadecylchlororing, and stirring at 150-160C. was then continued 2 hours longer. 7

Example 7.-To 0.05 mol of N -octadecy1chloroacetamide at 150-160 C. wasadded with stirring, dropwise and simultaneously, 3 grams (0.03 mol) ofethylene dichloride and 3 grams (0.03 mol) of diethylenetriamine. Themixture was then stirred at ISO-160 C. for 2 hours longer. It isbelieved that by this procedure, two molecules of the alkylatedchloroacetamide are joined through an amine-containing linkagerepresented by a large polyalkylenepolyamine.

Example 8.To 0.005 mol of N-tetradecylchloroacetamide at 150-l60 C. wasadded 0.26 grams (0.0025 mol) of diethylenetriamine, with stirring, andthen stirring at 150-160 C. was continued 2 hours longer.

Example 9.--A mixture of 2.5 grams of beta- 4 chlorobutyric acid and6.34 grams of octadecylamine (with a mean molecular weight of 264) wasstirred 2 hours at -l60 C. Then 1.4 cc. of diethylenetriamine was addedand the mixture stirred 3 hours longer at 150-160 C.

Example 10.-' -A mixture of 5 grams of betachloropropionyl chloride and6.7 grams of octadecylamine (with a mean molecular weight of 264) wasmade at room temperature, and quickly warmed itself to a homogeneousliquid mass, which was gradually heated, with stirring, to 150 C. Then1.4 cc. of diethylenetriamine was added and the mixture stirred 3 hoursat 150- C.

Example' 1J.- -10.6 grams of octadecylamine (having a mean molecularweight of 264) was added portion-wise to a melt of 10.7 grams ofo-iodobenzoyl chloride, and the mixture brought to 150 C. with stirring.Then 2.16 cc. of diethylenetriamine was added and the mixture stirred2*hours at 150-160" C.

These compounds, while not ordinarily considered as soluble in water toany great extent, may be suitably dispersed in water or emulsifiedtherewith, so that effective amounts thereof may be introduced and bepresent in the water within the steam generator under operatingconditions. The emulsifying or: dispersing agent used must, however, beof a kind that does not cause foaming, either by itself .or by itsdecomposition products. The compounds may be used conjointly with eachother as well as with other known antifoaming agents, such as, forexample, castor oil.

The amounts of the compounds hereinabove described which are requiredare extremely small, and in general one grain per gallon isample. Formany purposes, however, amounts of as little as /100 grain per gallon inthe feed water will stillgive valuable results, and the amounts may beeven further reduced. Depending of course upon the degree ofconcentration of solids, the dosage may be varied, but one grain pergallon is about as much as would ever have to be used even under seriousconditions, and for many purposes /1 0 grain per gallon and even lesscan be used. The process is particularly efiective at pressures of about2"50pounds per square inch.

The introduction of the aritifoaming compounds of the present inventioninto the boiler maybe accomplished in a number of ways. Thus, theantifoaming compositions may be dispersed or physically mixed with, say,sodium carbonate or some other material used for treatingthe boilerwaterand pumped with the feed water into the boiler by means of eitheran injector or a feed water pump. The compounds may also be dissolved insuitable organic water-miscible solvents such as alcohols, ethers,k'etones, etc., and introduced in small measured amounts into the feedwater entering the boiler. 'Suitable mechanical measuring devices whichwill periodically or continuously inject the required dosage of the antifoaming compounds into the feed water may be used, so that theintroduction will be more or less in proportion to the steam'consumptionto which the steam generator is subjected. Another manner of introducingthe antifoaming' compounds is to form an emulsion thereof in water andthen feed said emulsion either directly into the boiler or the feedwater lines leading to it. The invention therefore is not to be limitedby the manner of introduction of the anti-foaming composition but ratheris to be construed in the terms of the hereunto appended claims.

Iclalmz.

1. A method of generating steam which comprises boiling, unders'uperatmospheric pressure conditions, water containing an amount oftotal dissolved solids tending to produce foaming and priming and aquantity of the condensation product of about 2 mols ofN-octadecylchloroacetamide and 1 mol of diethylenetriamine, saidquantity being suflicient to substantially inhibit said foaming andpriming. 1

2. A method of generating steam which comprises boiling, undersuperatmospheric;pressure conditions, water containing an amount oftotal dissolved solids tending to produce foaming and priming and aquantity of the condensation prodnot of about 2 mols ofN-octadecylchloroacetamide and 1 mol of hydrazine, said quantity beingsufficient to substantially inhibit said foaming and priming.

3. A method of generating steam which comprises boiling, undersuperatmospheric pressure conditions, water containing an amount oftotal dissolved solids tending to produce foaming and priming and aquantity of the condensation product of about 2 mols of aN-octadecylchloroacetamide and 1 mol of piperazine, said quantity beingsufficient to substantially inhibit said foaming and priming.

4. A method of generating steam which comprises boiling, undersuperatmospheric pressure conditions, water containing an amount oftotal dissolved solids tending to produce foaming and priming and aquantity of the condensation product of about 2 mols of an N-alkylhalogeno organic acid amide and 1 mol of an organic polyamine having atleast two amino groups with replaceable hydrogen atoms, said aminogroups being connected by a group containing not more than 6 carbonatoms and the N-alkyl group containing at least 14 carbon atoms, saidquantity being sufiicient to substantially inhibit said foaming andpriming.

5. A method of generating steam which comprises boiling, undersuperatmospheric pressure conditions, water containing an amount oftotal dissolved solids tending to produce foaming and priming and aquantity of a compound having the following general formula in which Yrepresents an aliphatic radical containing at least about 14 carbonatoms; Z is the divalent hydrocarbon radical of a halogeno-acid; and Xis the residue from an organic polyamine whose terminal nitrogen atomsappear on either side of X in the above formula, the amino groups insaid organic polyamine being separated by not more than 6 carbon atomsand said quantity being sufiicient to substantially inhibit said formingand priming,

6. A liquid for the generation of steam substantially devoid of foamingand priming tendencies when heated to the boiling point, comprisingwater containing an amount of total dissolved solids tending to producefoaming and priming and a quantity of a condensation product of 2 molsof an N-alkyl halogeno organic acid amide and 1 mol of an organicpolyamine having at least two amino groups with replaceable hydrogenatoms, said amino groups being connected by a group containing not morethan 6 carbon atoms and the N-alkyl group containing at least 14 carbonatoms, said quantity being sufficient to substantially inhibit saidfoaming and priming.

'7. A liquid for the generation of steam, substantially devoid offoamin'g and priming tendencies "when'heated to the boiling-point,comprising-water containing an' amount of total diswherein Y is analiphatic radical cont'aininglat least 15i carbon atoms; -z is thedivalent"hydro-- .carbbnradical of ahalogeno-acid; and X is the residuefroman organic polyamine whose'terminal nitrogen atoms appear on eitherside of X in the above formula, the amino' groups in said organicpolyamine being separated by not more than 6 carbon atoms and saidquantity being sufficient to substantially inhibit said foaming andpriming.

8. A liquid for the generation of steam, substantially devoid of foamingand priming tendencies when heated to the boiling point, comprisingwater containing an amount of total dissolved solids tending to producefoaming and priming and a quantity of the condensation product of about2 mols of N-octadecylchloroacetamide and 1 mol of diethylenetriamine,said quantity being sufilcient to substantially inhibit said foaming andpriming.

9. A method Of generating steam which comprises boiling, undersuperatmospheric pressure conditions, water containing an amount oftotal dissolved solids tending to produce foaming and priming and aquantity of the condensation product of about 2 mols of an N-alkylhalogeno organic acid amide and about 1 mol of a polyethylene polyaminehaving two terminal primary amino groups, said N-alkyl group containingat least 14 carbon atoms, and said quantity being sufiicient tosubstantially inhibit said foaming and priming.

10. A liquid for the generation of steam substantially devoid of foamingand priming tendencies when heated to the boiling point, comprisingwater containing an amount of total dissolved solids tending to producefoaming and priming and a quantity of the condensation product of about2 mols of an N-alkyl halogeno organic acid amide and about 1 mol of apolyethylene polyamine having two terminal primary amino groups, saidN-alkyl group containing at least 14 carbon atoms, and said quantitybeing sufficient to substantially inhibit said foaming and priming.

11. A method of generating steam which comprises boiling, undersuperatmospheric pressure conditions, water containing an amount oftotal dissolved solids tending to produce foaming and priming and aquantity of the condensation product of about 2 mols ofN-octadecylchoroacetamide and 1 mol of M-phenylenediamine, said quantitybeing sufficient to substantially inhibit said foaming and priming.

12. A liquid for the generation of steam substantially devoid of foamingand priming tend encies when heated to the boiling point comprisingwater containing an amount of total dissolved solids tending to producefoaming and priming and a quantity of the condensation product of about2 mols of N-octadecylchloroacetamide and 1 mol of m-phenylenediamine,and said quantity being sufficient to substantially inhibit said foamingand priming.

13. A method of generating steam which comprises boiling, undersuperatmospheric pressure conditions, water containing an amount oftotal quantity being sufificient to substantially inhibit l said foamingand priming.

14. A liquid for the generation of steam substantiallydevoid of foamingand. priming tend encies when heated to the boilingpoini; comprisingwater containing an amount of total dis solved solids tending to produce{gaming and priming and a quantity of the condensation prodnot of about,2 mols of N -=octadecylchloroacetam.- ide and 1 mol oftriethylenetetramine, and saicl 8 quantity being sufii cient tosubstantially inhibit said roami g n pr m ng. r V

1 L. JACOBY.

REFERENCES CITED The following references are of record in, the file (ifthis patent:

UNITED STATES PATENTS- Number Name Date 1,892,857 spellmeyer Jan. 3,1933 2,304,805 Denman ...l =...l D66. 15', 1942 2,328,551 Guriderson er. Sept. 7, 1943 2,345,632 RObiIlSOn 6t 8,1. .-......l Apr. 4, 1944

4. A METHOD OF GENERATING STEAM WHICH COMPRISES BOILING, UNDERSUPERATMOSPHERIC PRESSURE CONDITIONS, WATER CONTAINING AN AMOUNT OFTOTAL DISSOLVED SOLIDS TENDING TO PRODUCE FOAMING AND PRIMING AND AQUANTITY OF THE CONDENSATION PRODUCT OF ABOUT 2 MOLS OF AN N-ALKYLHALOGENO ORGANIC ACID AMIDE AND 1 MOL OF AN ORGANIC POLYAMINE HAVING ATLEAST TWO AMINO GROUPS WITH REPLACEABLE HYDROGEN ATOMS, SAID AMINOGROUPS BEING CONNECTED BY A GROUP CONTAINING NOT MORE THAN 6 CARBONATOMS AND THE N-ALKYL GROUP CONTAINING AT LEAST 14 CARBON ATOMS, SAIDQUANTITY BEING SUFFICIENT TO SUBSTANTIALLY INHIBIT SAID FOAMING ANDPRIMING.